Ink jet printing has become a prominent contender in the digital output arena because of its non-impact, low-noise characteristics, and its compatibility with plain paper. Ink jet printing avoids the complications of toner transfers and fixing as in electrophotography, and the pressure contact at the printing interface as in thermal resistive printing technologies. Ink jet printing mechanisms include continuous ink jet or drop-on-demand ink jet. U.S. Pat. No. 3,946,398, which issued to Kyser et al. in 1970, discloses a drop-on-demand ink jet printer which applies a high voltage to a piezoelectric crystal, causing the crystal to bend, applying pressure on an ink reservoir and jetting drops on demand. Piezoelectric ink jet printers can also utilize piezoelectric crystals in push mode, shear mode, and squeeze mode. EP 827 833 A2 and WO 98/08687 disclose a piezoelectric ink jet print head apparatus with reduced crosstalk between channels, improved ink protection, and capability of ejecting variable ink drop size.
U.S. Pat. No. 4,723,129, issued to Endo et al, discloses an electrothermal drop-on-demand ink jet printer which applies a power pulse to an electrothermal heater which is in thermal contact with water based ink in a nozzle. The heat from the electrothermal heater produces vapor bubble in the ink, which causes an ink drop to be ejected from a small aperture along the edge of the heater substrate. This technology is known as Bubblejet.TM. (trademark of Canon K.K. of Japan).
One problem related to ink jet printing is related to insufficient drying of the ink of the ink droplets that are placed on the ink receiver during or after printing. In the field of ink jet printing, the term "drying" typically refers to drying through evaporation as well as drying by absorption of ink fluid into the receiver. For color and photographic printing, it is often desirable to coat an ink absorption layer on the receiver to assist the ink absorption. When ink drops are not dried fast enough, several image artifacts can occur. One type of image artifact is called coalescence, that is, wet ink drops on the receiver paddled together and causes a glossiness change in the area of the ink paddle. The insufficient drying can also cause wet ink of one color on the receiver to diffuse into the ink area of a different color, which produces a "color bleeding" image artifact.
Another problem related to the above is that the image quality and other ink jet printing performance are often sensitive to the environment variation. One cause for this problem is that the relative humidity in the environment affects the amount of the moisture stored in the receiver. With high moisture content, the ability of the ink absorption by the receiver is reduced. The drying rate of ink drops on receiver is decreased. A receiver with high moisture content can also affect how accurately the receiver can be transported. The receiver driving rollers can slip at the interface between the roller and the receiver surface.